Variable-phase S-matrix calculations for asymmetric potentials and dielectrics

摘要

Motivated by recently developed techniques making it possible to compute Casimir energies for any objectnwhose scattering S matrix (or, equivalently, T matrix) is available, we develop a variable phase method toncompute the S matrix for localized but asymmetric sources. Starting from the case of scalar potential scattering,nwe develop a combined inward-outward integration algorithm that is numerically efficient and extends robustlynto imaginary wave number.We then extend these results to electromagnetic scattering from a position-dependentndielectric. This case requires additional modifications to disentangle the transverse and longitudinal modes.